1. Field of the Invention
The present invention relates to indicating instruments mounted on automobiles and motorcycles and, more particularly, to indicating instruments comprising a moving magnet type instrument for use in a fuel gauge, a temperature indicator, an engine tachometer, a speedometer, a voltmeter, etc.
2. Description of the Prior Art
This type of instruments have been disclosed for example in U.S. Pat. No. 3,694,750 or in Japanese Utility Model Publication No. Sho 61-115,973. According to these prior-art instruments, as shown in FIG. 14, a magnet 2 is assembled in a synthetic resin bobbin 1; to this magnet 2 is fixedly installed a needle shaft 3. This needle shaft 3 is inserted from the tube section 4 projectingly mounted at center in the upper part of the bobbin 1, on which coils 5 are wound at an angle, and shaft-like terminals 7 are inserted through, and fixed in, a leg section 6 formed integral with the peripheral side section of the bobbin 1. To these terminals 7 are electrically connected the coils 5. The whole body of the bobbin 1 is contained in a metallic bottomed magnetic shielding case 10 consisting of a peripheral side section 8 and a bottom section 9 for protection from a disturbance factor such as earth magnetism, and terminals 7 are electrically connected to a printed-circuit board 11, so that the magnet 2 will be driven to make an angular motion by a composite magnetic field which is formed in accordance with the quantity of electric current flow into the coils 5. Such instruments have the following problem that since the terminals 7 are positioned within the magnetic shielding case and the coils are electrically connected to the terminals 7 within this magnetic shielding case 10, the magnetic shielding case tends to become large in size. To solve this problem, the terminals are mounted outside of the magnetic shielding case, whereby the magnetic shielding case can be made small in size as proposed in Japanese Utility Model Publication No. Sho 63-153,174. That is to say, as shown in FIGS. 15 and 16, a vertical groove-shaped case inserting section 12 is provided in the inward part of the leg section 6, and in this case inserting section 12 is inserted over the peripheral side section 8 of the magnetic shielding case 10 from an opening side such that the leg section 6 will be mounted in the outward position of the magnetic shield case 10. Through this leg section 6 in this outward position is inserted a thin pin-like terminals 7A and each coil end 5A of the coils 5 are wound around, and soldered to, the upper end section of this terminals 7A.
In various types of moving coil type instruments, there are provided a plurality of projections 13 around a lower part of the bobbin 1 for the purpose of fixedly attaching the magnetic shielding case 10 as shown in FIGS. 15 to 71. These projections 13 are inserted into holes 14 made in the bottom section 9 of the magnetic shielding case 10 and welded, thus forming a welded section 15.
In the above-described prior-art technique, each coil end 5A of the coils 5, as shown in FIGS. 15 and 16, is wound around on the top end of the terminals 7A astride the opening section of the magnetic shielding case 10, from the inside to the outside, Because these coil ends 5A are provided with slack to prevent the coils 5 from wire breakage likely to be caused by thermal shrinkage, each coils end 5A of the coil 5 comes off from the leg section 6, becoming likely to contact the magnetic shielding case 10. This contact of the coil end 5A with the case 10 will cause an electrical fault in characteristics and wire breakage of the coils 5.
Furthermore, there is also such a problem that since the magnetic shielding case 10, as shown in FIGS. 15 and 16, contains the bobbin 1 wound with the coils 5 therein with the peripheral side section 8 inserted in the groove-like case inserting section 12, the bobbin 1 is restricted, in the height range enclosed with the magnetic shielding case 10, by the case inserting section 12, and accordingly the coils 5 partly protrude out upward of the magnetic shielding case 10, resulting in insufficient magnetic shielding effect. Furthermore, there exists such a problem that the projections provided around the lower part of the bobbin 1 are inserted in the holes 14 made in the flat bottom section 9 of the magnetic shielding case 10 as shown in FIG. 17 and welded at the weld-fixing part 15 as shown in FIG. 15; this weld-fixing part 15 fixedly attached the magnetic shielding case 10 to the bobbin 1, protruding downward out of the bottom section 9 of the magnetic shielding case 10, such that the protruding section increases the height of the moving magnet-type instrument as the whole, and moreover the outside bottom surface of the magnetic shielding case 10 can not be set as a reference bottom surface, and therefore dimensional designing of the instrument is difficult to perform.